Non-contact charging module, electronic apparatus, and non-contact charging apparatus

ABSTRACT

This non-contact charging module can be suitably used by suppressing a change of an L value of a coil that is provided in the non-contact charging module, and achieves size reduction, even in the cases where a magnet that is provided in the other non-contact charging module is used or not used. The module is characterized in that: the module is provided with a primary side coil (21a) wherein a conducting line is wound in a substantially rectangular shape, and a magnetic sheet (51) that is provided with a surface on which the primary side coil (21a) is placed; and that a substantially rectangular-shaped hollow portion of the primary side coil (21a) has the short side thereof shorter than the diameter of a circular magnet (30a), and the long side thereof longer than the diameter of the circular magnet (30a).

TECHNICAL FIELD

The present invention relates to a non-contact charging module having aplanar coil portion and a magnetic sheet, and an electronic device and anon-contact charging device.

BACKGROUND ART

Recently, there have been utilized a number of apparatuses with a mainunit which can be charged in a non-contact manner by a charger. In suchapparatuses, non-contact charging modules are respectively provided at acharger side and a main unit side and electromagnetic induction iscaused between both modules so that power is transmitted from thecharger side to the main unit side. It has been also proposed to apply amobile terminal device or the like as the main unit.

There is a need for thinner and smaller main unit and charger for themobile terminal device, or the like. To respond to such a need, asdisclosed in Patent Literature 1, it is considered to provide a planarcoil portion and a magnetic sheet, which serve as a transmission sidenon-contact charging module and a reception side non-contact chargingmodule.

CITATION LIST Patent Literature

-   PTL 1-   Japanese Patent Application Laid-Open No. 2006-42519

SUMMARY OF INVENTION Technical Problem

Such types of non-contact charging modules require to position a primaryside non-contact charging module (transmission side non-contact chargingmodule) and a secondary side non-contact charging module (reception sidenon-contact charging module) accurately to efficiently causeelectromagnetic induction for power transmission.

In order to position the primary side non-contact charging module(transmission side non-contact charging module) and the secondary sidenon-contact charging module (reception side non-contact charging module)accurately, one method is to use a magnet, an example of which is amethod shown in FIG. 11. FIG. 11 illustrates a non-contact chargingmodule (for example, a secondary side non-contact charging module)brought into position by a magnet provided at the other non-contactcharging module (for example, a primary side non-contact chargingmodule). In this method, the primary side non-contact charging moduleand the secondary side non-contact charging module are positioned by amagnet provided at at least one of the modules so that the magnetsprovided at the both modules or the magnet provided at one module and amagnetic sheet provided at the other module attract each other.

Further, there is another method in which the primary side non-contactcharging module and the secondary side non-contact charging module arepositioned accurately without utilizing a magnet.

For example, there is a method in which the primary side non-contactcharging module and the secondary side non-contact charging module arephysically (as a shape) and forcibly positioned by fitting a protrudingportion formed on a charging surface of a charger provided with theprimary side non-contact charging module into a recessed portion formedat an electronic device provided with the secondary side non-contactcharging module. There is still another method in which the primary sidenon-contact charging module detects a position of a coil of thesecondary side non-contact charging module to thereby automatically movea coil of the primary side non-contact charging module to the positionof the coil of the secondary side non-contact charging module. There isyet another method in which a large number of coils are provided at acharger to thereby enable charging even if a mobile device is placed atanywhere on a charging surface of the charger.

However, L values of the coils provided at the respective non-contactcharging modules largely vary between a case where a magnet is used forpositioning the primary side non-contact charging module and thesecondary side non-contact charging module and a case where a magnet isnot used. Resonant frequency of the electromagnetic induction for powertransmission is determined by utilizing the L values of the coilsprovided at the respective non-contact charging modules.

Accordingly, there is a problem in that it is difficult to share thenon-contact charging modules between a case where a magnet is used forpositioning the primary side non-contact charging module and thesecondary side non-contact charging module and a case where a magnet isnot used.

Therefore, an object of the present invention is to provide anon-contact charging module which can suppress variation of an L valueof a coil provided at the non-contact charging module in both of a casewhere a magnet provided at the other non-contact charging module servingas a counterpart for power transmission is used and a case where amagnet is not used for positioning a primary side non-contact chargingmodule and a secondary side non-contact charging module, and which canbe suitably used in both of a case where a magnet is used and a casewhere a magnet is not used, and which can realize downsizing, and alsoto provide an electronic device and a non-contact charging device.

Solution to Problem

A non-contact charging module according to an aspect of the presentinvention is configured to be positioned with another non-contactcharging module using a circular magnet or without using the circularmagnet for positioning, the circular magnet being provided at the othernon-contact charging module, the non-contact charging module including:a planar coil portion including a conductive wire wound in asubstantially rectangular shape; and a magnetic sheet provided with asurface on which the planar coil portion is placed, in which the planarcoil portion includes a substantially rectangular hollow portion thathas a short side shorter than a diameter of the circular magnet and along side longer than the diameter of the circular magnet.

Advantageous Effects of Invention

According to the present invention, it is possible to provide anon-contact charging module which can suppress variation of an L valueof a coil provided at the non-contact charging module in both of a casewhere a magnet provided at the other non-contact charging module servingas a counterpart for power transmission is used and a case where amagnet is not used for positioning a primary side non-contact chargingmodule and a secondary side non-contact charging module, and which canbe suitably used in both of a case where a magnet is used and a casewhere a magnet is not used, and which can realize downsizing and toprovide a non-contact charging device using the non-contact chargingmodule.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a non-contact power transmissiondevice according to an embodiment of the present invention;

FIG. 2 illustrates a configuration of a non-contact charger according tothe embodiment of the present invention;

FIG. 3 illustrates a primary side non-contact charging module accordingto the embodiment of the present invention;

FIGS. 4A to 4D illustrate in detail the primary side non-contactcharging module according to the embodiment of the present invention;

FIG. 5 illustrates a configuration of a mobile terminal device accordingto the embodiment of the present invention;

FIG. 6 illustrates a secondary side non-contact charging moduleaccording to the embodiment of the present invention;

FIGS. 7A to 7D illustrate in detail the secondary side non-contactcharging module according to the embodiment of the present invention;

FIGS. 8A to 8D illustrate a relationship between the primary sidenon-contact charging module provided with a magnet and the secondaryside non-contact charging module;

FIG. 9 illustrates a relationship between a coil inner diameter and an Lvalue of the coil;

FIGS. 10A and 10B illustrate a positional relationship between asecondary side coil wound in a rectangular shape and a secondary sidecoil wound in a circular shape, and a magnet provided at the primaryside non-contact charging module; and

FIG. 11 illustrates a non-contact charging module (for example, thesecondary side non-contact charging module) brought into position usinga magnet provided at the other non-contact charging module (for example,the primary side non-contact charging module).

DESCRIPTION OF EMBODIMENTS Embodiment

An embodiment of the present invention will be described below withreference to the accompanying drawings.

(Regarding a Non-Contact Charging System)

FIG. 1 is a block diagram illustrating a non-contact power transmissiondevice according to an embodiment of the present invention.

The non-contact power transmission device includes primary sidenon-contact charging module 41 (transmission side non-contact chargingmodule) and secondary side non-contact charging module 42 (receptionside non-contact charging module), and transmits power from primary sidenon-contact charging module 41 to secondary side non-contact chargingmodule 42 by utilizing the action of electromagnetic induction. Thisnon-contact power transmission device is used for transmitting power ofapproximately 5 W or lower and has a frequency of power transmissionbetween approximately 110 and 205 kHz. Primary side non-contact chargingmodule 41 is mounted on, for example, a charger, and secondary sidenon-contact charging module 42 is mounted on, for example, a mobilephone, a digital camera, a PC, or the like.

Primary side non-contact charging module 41 includes primary side coil21a, magnetic sheet 51, a resonant capacitor (not shown) and power inputsection 71. Power input section 71 is connected to commercial powersource 300 as an external power source to receive supply of power ofapproximately 100 to 240V, converts the power into predetermined currentA (DC 12V, 1 A) and supplies the current to primary side coil 21a.Primary side coil 21a generates a magnetic field according to its shape,the number of turns, and the supplied current. The resonant capacitor isconnected to primary side coil 21a and determines a resonant frequencyof the magnetic field generated from primary side coil 21a according toa relationship with primary side coil 21a. The action of electromagneticinduction from primary side non-contact charging module 41 to secondaryside non-contact charging module 42 occurs by this resonant frequency.

Meanwhile, secondary side non-contact charging module 42 includessecondary side coil 21b, magnetic sheet 52, a resonant capacitor (notshown), rectifier circuit 72 and power output section 82. Secondary sidecoil 21b receives the magnetic field generated from primary side coil21a, converts the magnetic field into predetermined current B byelectromagnetic induction action and outputs predetermined current B tothe outside of secondary side non-contact charging module 42 viarectifier circuit 72 and power output section 82. Rectifier circuit 72rectifies predetermined current B which is an alternating current toconvert the current into predetermined current C (DC 5V, 1.5 A) which isa direct current. Further, power output section 82 is a unit foroutputting power to the outside of secondary side non-contact chargingmodule 42, through which power is supplied to electronic device 200connected to secondary side non-contact charging module 42.

It should be noted that, as shown in FIG. 1, it is not necessary thatboth of primary side coil 21a of primary side non-contact chargingmodule 41 and secondary side coil 21b of secondary side non-contactcharging module 42 be a planar coil wound in a substantially rectangularshape. That is, though described in detail later, because the presentinvention is intended to stabilize transmission efficiency whether amagnet is provided or not provided at a counterpart (secondary sidenon-contact charging module 42 for primary side non-contact chargingmodule 41, and primary side non-contact charging module 41 for secondaryside non-contact charging module 42), a substantially rectangular coilmay be used in only one of the non-contact charging modules.

[Regarding a Non-Contact Charger and a Primary Side Non-Contact ChargingModule]

A case where primary side non-contact charging module 41 is mounted on anon-contact charger will be described.

FIG. 2 illustrates a configuration of a non-contact charger according tothe embodiment of the present invention. It should be noted that FIG. 2illustrates the configuration so that the inside of the non-contactcharger can be seen.

Non-contact charger 400 which transmits power by utilizing the action ofelectromagnetic induction has primary side non-contact charging module41 in a casing that forms the exterior of non-contact charger 400.

Non-contact charger 400 has a plug 401 which is inserted into outlet 301of commercial power source 300 provided indoors or outdoors. Non-contactcharger 400 can receive power supply from commercial power source 300 byplug 401 being inserted into outlet 301.

Non-contact charger 400 is provided on table 501, and primary sidenon-contact charging module 41 is arranged near surface 402 ofnon-contact charger 400 which is an opposite side of a surface of thetable. A primary flat surface of primary side coil 21a in primary sidenon-contact charging module 41 is arranged parallel to surface 402 ofnon-contact charger 400 which is an opposite side of the surface of thetable. This configuration makes it possible to secure an area for powerreception operation of the electronic device provided with secondaryside non-contact charging module 42. It should be noted that non-contactcharger 400 may be provided on a wall surface, in which case non-contactcharger 400 is arranged near a surface which is an opposite side of thewall surface.

Further, primary side non-contact charging module 41 may have magnet 30ato be used for performing positioning with secondary side non-contactcharging module 42, in which case magnet 30a is arranged in a hollowportion positioned in a central area of primary side coil 21a.

Primary side non-contact charging module 41 will be described.

FIG. 3 illustrates a primary side non-contact charging module accordingto the embodiment of the present invention and illustrates a case wherea primary side coil is a substantially rectangular coil.

Primary side non-contact charging module 41 includes primary side coil21a which is a conductive wire wound in a spiral manner to form asubstantially rectangular shape, and magnetic sheet 51 provided to facea surface of primary side coil 21a.

As shown in FIG. 3, a planar coil portion of primary side non-contactcharging module 41 includes primary side coil 21a which is a conductorwound toward an outer direction in a spiral manner so as to form asubstantially rectangular shape on the surface, and terminals 22a and23a which are provided at both ends of primary side coil 21a as currentsupply portions. That is, terminals 22a and 23a which are current supplyportions supply a current from commercial power source 300 which is anexternal power source to primary side coil 21a. Primary side coil 21a isformed of a conductive wire wound on a plane in a parallel manner, and asurface formed by the coil is referred to as a coil surface. It shouldbe noted that a thickness direction is a direction in which primary sidecoil 21a and magnetic sheet 51 are stacked.

Magnetic sheet 51 includes flat portion 31a on which primary side coil21a is mounted, central portion 32a which is located at a center of flatportion 31a and which corresponds to a hollow area of primary side coil21a, and linear recessed portion 33a into which part of a drawn wire ofprimary side coil 21a is inserted. Central portion 32a may take any formamong a protruding shape, a flat shape, a recessed shape and a throughhole relative to flat portion 31a. If central portion 32a has aprotruding shape, it is possible to strengthen a magnetic flux ofprimary side coil 21a. If central portion 32a is flat, central portion32a can be easily manufactured, and primary side coil 21a can be easilymounted thereon, and it is possible to maintain a well-balancedrelationship between the influence of a magnet for positioning and an Lvalue of primary side coil 21a, which will be described later. Ifcentral portion 32a has a recessed shape or is a through hole, it ispossible to suppress the influence of a magnet for positioning. That is,it is possible to physically keep a distance between magnet 30b providedat secondary side non-contact charging module 42 and magnetic sheet 51,so that it is possible to prevent reduction of magnetic permeability asa result of magnetic sheet 51 being saturated by magnet 30b.Accordingly, it is possible to prevent an L value of primary side coil21a from varying according to the presence or absence of magnet 30b.Further, the recessed portion, the protruding portion or the throughhole may be formed in the same shape and to have the same size as thehollow portion, or may be formed in a different shape and may be smallerthan the hollow portion.

In primary side non-contact charging module 41 in this embodiment,primary side coil 21a is wound toward outside from a substantiallyrectangular hollow portion of approximately 12 mm×18 mm, and its outerend forms a rectangle of approximately 18 mm×23 mm. That is, primaryside coil 21a is wound in a substantially rectangular doughnut shape. Itshould be noted that “substantially rectangular” refers to a rectanglethat may include R (curved portion) at four corners.

Further, by winding the conductive wire so as to keep space from eachother, floating capacitance between an upper stage conductive wire and alower stage conductive wire becomes small, so that it is possible tosuppress alternating-current resistance of primary side coil 21a.Further, by winding the conductive wire so as to reduce space, it ispossible to reduce the thickness of primary side coil 21a.

Further, primary side non-contact charging module 41 may have magnet 30ato be used for performing positioning with secondary side non-contactcharging module 42. It is defined by the standards (WPC) that magnet 30ashould have a circular shape and should have a diameter of 15.5 mm orless and so on. Magnet 30a has a coin shape and has to be arranged sothat its center matches a central winding axis of primary side coil 21ain order to reduce influence of magnet 30a on primary side coil 21a.When magnet 30a is provided, it is preferable to provide a hollowportion larger than magnet 30a.

When primary side non-contact charging module 41 has magnet 30a, as thefirst method for arranging magnet 30a, there is a method in which magnet30a is arranged on an upper surface of central portion 32a of magneticsheet 51. Further, as the second method for arranging magnet 30a, thereis a method in which magnet 30a is arranged in place of central portion32a of magnetic sheet 51. In the second method, because magnet 30a isarranged in a hollow area of primary side coil 21a, it is possible tomake primary side non-contact charging module 41 smaller.

When a magnet is not utilized for positioning primary side non-contactcharging module 41 and secondary side non-contact charging module 42,magnet 30a shown in FIG. 3 is not required.

Influence of a magnet on power transmission efficiency of thenon-contact charging module will be described. Generally, a magnet isprovided inside a hollow portion of built-in primary side coil 21a orsecondary side coil 21b in at least one of the primary side non-contactcharging module and the secondary side non-contact charging module. Bythis means, it is possible to bring the magnet and the magnet or tobring the magnet and magnetic sheet 51 as close as possible to eachother and it is possible to bring the primary side coil and thesecondary side coil close to each other. The magnet has a circularshape. In this embodiment, the magnet has a diameter of approximately15.5 mm (approximately 10 mm to 20 mm), and a thickness of approximately1.5 to 2 mm. Further, a neodymium magnet is used, and strength may beapproximately 75 mT to 150 mT. In this embodiment, because there is aninterval of approximately 2 to 5 mm between the coil of primary sidenon-contact charging module and the coil of secondary side non-contactcharging module, it is possible to position the non-contact chargingmodules with a magnet having such a degree of strength.

When a magnetic flux is generated between primary side coil 21a andsecondary side coil 21b to transmit power, if a magnet exists between oraround primary side coil 21a and secondary side coil 21b, the magneticflux extends while avoiding the magnet. Alternatively, a magnetic fluxwhich penetrates inside the magnet causes an eddy current or heat insidethe magnet, which becomes a loss. Further, as a result of the magnetbeing arranged near the magnetic sheet, magnetic permeability of themagnetic sheet near the magnet is lowered. Accordingly, magnet 30aprovided at primary side non-contact charging module 41 reduces L valuesof both primary side coil 21a and secondary side coil 21b. As a result,transmission efficiency between the non-contact charging modules isreduced.

FIGS. 4A to 4D illustrate in detail the primary side non-contactcharging module according to the embodiment of the present invention.FIG. 4A illustrates an upper surface of the primary side non-contactcharging module, FIG. 4B illustrates a cross-section taken along A-A ofthe primary side non-contact charging module in FIG. 4A, FIG. 4Cillustrates a cross-section taken along B-B of the primary sidenon-contact charging module in FIG. 4A when a linear recessed portion isprovided, and FIG. 4D illustrates a cross-section taken along B-B of theprimary side non-contact charging module in FIG. 4A when a slit isprovided. It should be noted that FIG. 4A and FIG. 4B illustrate a casewhere magnet 30a is not provided, and if a magnet is provided, magnet30a indicated by the dotted line is provided.

Primary side coil 21a is formed to have two stages in a thicknessdirection from a winding start portion positioned in the central area ofprimary side coil 21a to terminal 23a and to have one stage in theremaining area in order to realize thinner non-contact charger 400 onwhich primary side non-contact charging module 41 is mounted. Inaddition, the conductive wire is wound so as to keep space between theupper stage conductive wire and the lower stage conductive wire, therebyreducing floating capacitance between the upper stage conductive wireand the lower stage conductive wire, so that it is possible to suppressalternating-current resistance of primary side coil 21a.

When conductive wires are stacked to extend primary side coil 21a in athickness direction of primary side non-contact charging module 41, itis possible to increase a current flowing through primary side coil 21aby increasing the number of turns of primary side coil 21a. When theconductive wires are stacked, by winding the conductive wire so as toreduce space between the upper stage conductive wire and the lower stageconductive wire, it is possible to increase a current flowing throughprimary side coil 21a while suppressing the thickness of primary sidecoil 21a. Further, by stacking the conductive wire in the thicknessdirection, because magnetic sheet 51 is positioned away from secondaryside non-contact charging module 42 though primary side coil 21a ispositioned close to secondary side non-contact charging module 42, it ispossible to suppress influence of magnet 30b when magnet 30b is providedat secondary side non-contact charging module 42. Further, this can beapplied to a relationship between magnet 30a of primary side non-contactcharging module 41, and secondary side coil 21b and magnetic sheet 52.Influence of magnets 30a and 30b will be described later.

While in this embodiment, primary side coil 21a is formed using aconductive wire having a circular cross section, it is also possible touse a conductive wire having a rectangular or polygonal cross section.When a conductive wire having a circular cross section is used, becausea gap occurs between adjacent parts of the conductive wire, floatingcapacitance between the parts of the conductive wire becomes small, sothat it is possible to suppress alternating-current resistance ofprimary side coil 21a.

Further, compared to a case where the conductive wire of primary sidecoil 21a is wound in two stages in a thickness direction,alternating-current resistance of primary side coil 21a becomes lowerand transmission efficiency can increase when the conductive wire iswound in one stage. This is because, when the conductive wire is woundin two stages, floating capacitance occurs between the upper stageconductive wire and the lower stage conductive wire. Accordingly, it ispreferable to wind the conductive wire in one stage in as large portionas possible rather than to wind the conductive wire in two stages in thewhole primary side coil 21a. Further, by winding the conductive wire inone stage, it is possible to make primary side non-contact chargingmodule 41 thinner. Further, when planar coil portion 2 includes twoconductive wires, because the two conductive wires are electricallyconnected by a solder, or the like, at the portions of terminals 22a and23a, the two conductive wires may be formed as if it were one thickconductive wire. The two conductive wires may be wound side by side inparallel to a coil surface or may be wound side by side vertically withrespect to the coil surface. That is, when the conductive wires arewound in parallel to the coil surface, the two conductive wires arewound around the same central axis in a planar shape, and one conductivewire is put between the other conductive wires in a radial direction. Byelectrically bonding the two conductive wires at the portions ofterminals 22a and 23a in this way so that the two conductive wiresfunction as if it were one conductive wire, it is possible to suppressthe thickness while maintaining the same cross-sectional area. That is,it is possible to obtain a cross-sectional area of a conductive wirehaving a diameter of 0.25 mm with two conductive wires having a diameterof 0.18 mm, for example. Accordingly, while if one conductive wirehaving a diameter of 0.25 mm is used, the thickness of one turn ofprimary side coil 21a is 0.25 mm and the width of primary side coil 21ain a radial direction is 0.25 mm, if two conductive wires having adiameter of 0.18 mm are used, the thickness of one turn of primary sidecoil 21a is 0.18 mm and the width in a radial direction is 0.36 mm. Itshould be noted that the thickness direction is a direction in whichprimary side coil 21a and magnetic sheet 51 are stacked. Further, theconductive wires are overlapped in two stages in the thickness directionat only part at the central side of primary side coil 21a, and theconductive wires may be formed in one stage at the remaining outerportion. Further, if the conductive wires are wound vertically withrespect to the coil surface, while the thickness of primary sidenon-contact charging module 41 increases, because the cross-sectionalarea of the conductive wires virtually increases, it is possible toincrease a current flowing through primary side coil 21a and to easilysecure a sufficient number of turns. It should be noted that in thisembodiment, primary side coil 21a includes conductive wires ofapproximately 0.18 to 0.4 mm, and among them, it is preferable to use aconductive wire of 0.25 to 0.35 mm for primary side coil 21a of primaryside non-contact charging module 41.

Because the alternating-current resistance of primary side coil 21a islow, it is possible to prevent a loss at primary side coil 21a, and byincreasing an L value, it is possible to improve power transmissionefficiency of primary side non-contact charging module 41 which dependson the L value.

While terminals 22a and 23a may be provided close to each other orseparate from each other, primary side non-contact charging module 41can be easily mounted if terminals 22a and 23a are provided separatefrom each other.

Magnetic sheet 51 which is provided to improve power transmissionefficiency of non-contact charging utilizing electromagnetic inductionaction, includes planar portion 31a, central portion 32a which is acenter of coil 21, and linear recessed portion 33a. Further, if magnet30a for positioning primary side non-contact charging module 41 andsecondary side non-contact charging module 42 is provided, magnet 30amay be provided above central portion 32a or may be provided in place ofcentral portion 32a.

Further, it is possible to use a Ni—Zn ferrite sheet, a Mn—Zn ferritesheet, a Mg—Zn ferrite sheet, or the like as magnetic sheet 51. Magneticsheet 51 may be formed as a single layer structure or as a structure inwhich a plurality of layers of the same material are laminated in athickness direction, or may be formed by laminating a plurality oflayers of different magnetic sheets 51 in the thickness direction. It ispreferable to use magnetic sheet 51 having at least magneticpermeability of 250 or higher and saturation magnetic flux density of350 mT or higher.

Further, it is possible to use an amorphous metal as magnetic sheet 51.When a ferrite sheet is used as magnetic sheet 51, thealternating-current resistance of primary side coil 21a isadvantageously reduced, while, when an amorphous metal is used as themagnetic sheet, it is possible to make primary side coil 21a thinner.

Magnetic sheet 51 to be used for primary side non-contact chargingmodule 41 has a size within approximately 50×50 mm, and has a thicknessof approximately 3 mm or less. In this embodiment, magnetic sheet 51 isa substantially rectangle of approximately 20 mm×25 mm. It is preferablethat magnetic sheet 51 is formed so as to have about the same size as orlarger than the outer circumference end of primary side coil 21a.Further, the shape of magnetic sheet 51 may be a circle, a rectangle, apolygon, or a rectangle or a polygon having large curves at fourcorners.

Linear recessed portion 33a or slit 34a store the conductive wire from acoil winding start portion (innermost portion of the coil) to aterminal. By this means, it is possible to prevent the conductive wirefrom the coil winding start portion to the terminal from overlapping inthe thickness direction of primary side coil 21a and suppress thethickness of primary side non-contact charging module 41. Further, bysetting the size of linear recessed portion 33a or slit 34a to a minimumsize which can store the conductive wire from the coil winding startportion to the terminal, it is possible to suppress occurrence of aleakage flux. Further, as shown in FIG. 3, linear recessed portion 33aor slit 34a does not have to be extended in parallel to a long sidedirection of primary side coil 21a, but may be parallel to a short sidedirection. Further, the cross-sectional shape of linear recessed portion33a does not have to be a rectangle, but may be an arc or a round.

Linear recessed portion 33a or slit 34a is formed so as to besubstantially perpendicular to an end of magnetic sheet 51 whichintersects with an end of linear recessed portion 33a or slit 34a, andso as to overlap with an outline (sides of a substantially rectangularhollow portion) of the hollow portion. By forming linear recessedportion 33a or slit 34a in this way, it is possible to form terminals22a and 23a without bending the conductive wire at the winding startportion. The length of linear recessed portion 33a or slit 34a dependson the size of the hollow portion of coil 21 and, in this embodiment, isapproximately 5 mm to 15 mm.

Further, linear recessed portion 33a or slit 34a may be formed at aportion where the end of magnetic sheet 51 comes closest to the windingstart portion of primary side coil 21a located at the end of the hollowportion. By this means, it is possible to minimize the area for forminglinear recessed portion 33a or slit 34a and improve transmissionefficiency of the non-contact power transmission device. In this case,the length of linear recessed portion 33a or slit 34a is approximately 5mm to 10 mm. An inner end of linear recessed portion 33a or slit 34a isconnected to central portion 32a for either arrangement.

Further, linear recessed portion 33a or slit 34a may be arranged inother manners. That is, because it is preferable to form primary sidecoil 21a to have a single stage structure, it is conceivable to adopt anarrangement where all the turns in a radial direction of primary sidecoil 21a are formed in one stage structure, or an arrangement where partof the turns is formed in a single stage structure and the other part isformed in a two-stage structure. Accordingly, while it is possible todraw one of terminals 22a and 23a from an outer periphery of primaryside coil 21a, the other terminal has to be drawn from the inside. If aportion where primary side coil 21a is wound certainly overlaps with aportion from winding end of primary side coil 21a to terminal 22a or 23ain a thickness direction, linear recessed portion 33a or slit 34a may beprovided at the overlapped portion.

If linear recessed portion 33a is used, because a through hole or a slitis not provided at magnetic sheet 51, it is possible to prevent leakageof a magnetic flux and improve power transmission efficiency of primaryside non-contact charging module 41. Meanwhile, when slit 34a is used,magnetic sheet 51 can be easily formed. If linear recessed portion 33ais used, the cross-sectional shape is not limited to a rectangle, butmay be an arc or a round.

Then, an influence of a magnet on primary side non-contact chargingmodule 41 and secondary side non-contact charging module 42 which willbe described later will be described. Secondary side coil 21b insidesecondary side non-contact charging module 42 receives a magnetic fieldgenerated by primary side non-contact charging module 41 to performpower transmission. If a magnet is arranged around primary side coil 21aand secondary side coil 21b, the magnetic field may be generated whileavoiding the magnet or the magnetic field which tries to pass throughthe magnet may disappear. Further, magnetic permeability at a portionclose to the magnet of magnetic sheet 51 is reduced. That is, themagnetic field is weakened by the magnet. Accordingly, in order tominimize the magnetic field weakened by the magnet, it is necessary totake some measures such as separating primary side coil 21a andsecondary side coil 21b and the magnet or providing magnetic sheet 51which is less likely to be influenced by the magnet.

Because primary side non-contact charging module 41 is used at a fixedterminal which is a power supply transmission side, there is extra spacewhich can be occupied by primary side non-contact charging module 41 inthe fixed terminal. Further, because a current flowing through primaryside coil 21a of primary side non-contact charging module 41 is large,insulation property of magnetic sheet 51 is important. If magnetic sheet51 is a conductive sheet, a large current flowing through primary sidecoil 21a may be transmitted to other parts via magnetic sheet 51.

In consideration of the above, magnetic sheet 51 mounted on primary sidenon-contact charging module 41 is preferably a (insulation) Ni—Znferrite sheet having a thickness of 400 μm or greater (preferably, 600μm to 1 mm), magnetic characteristic of magnetic permeability of 250 orhigher, and saturation magnetic flux density of 350 mT or higher.However, it is also possible to use a (conductive) Mn—Zn ferrite sheetif being subject to sufficient insulation processing, in place of theNi—Zn ferrite sheet.

Further, in primary side non-contact charging module 41, the L value ofprimary side coil 21a of primary side non-contact charging module 41largely varies between a case where magnet 30a is used for positioningand a case where magnet 30a is not used. That is, the presence of magnet30a in primary side non-contact charging module 41 or the presence of asimilar magnet in secondary side non-contact charging module 42 inhibitsthe magnetic flux between the primary side and the secondary sidenon-contact charging modules, and largely reduces the L value of primaryside coil 21a of primary side non-contact charging module 41 by thepresence of the magnet. In order to suppress the influence of thismagnet 30a, magnetic sheet 51 is preferably formed with a highsaturation magnetic flux density material (having saturation magneticflux density of 350 mT or higher). Because the high saturation magneticflux density material has property that a magnetic flux is less likelyto be saturated even if the magnetic field becomes strong, it ispossible to reduce influence of magnet 30a and improve the L value ofcoil 21 when magnet 30a is used. Accordingly, it is possible to makemagnetic sheet 51 thinner.

However, if the magnetic permeability of magnetic sheet 51 becomes toolow, the L value of primary side coil 21a is significantly lowered. As aresult, the efficiency of primary side non-contact charging module 41may be degraded. Accordingly, the magnetic permeability of magneticsheet 51 is preferably at least 250 or higher, more preferably, 350 orhigher. Further, while the L value also depends on the thickness ofmagnetic sheet 51, the thickness of the ferrite sheet may be 400 μm orgreater. While the ferrite sheet can reduce the alternating-currentresistance of coil 21 compared to the magnetic sheet of the amorphousmetal, it is also possible to use the amorphous metal. By using suchmagnetic sheet 51, even if at least one of primary side non-contactcharging module 41 and secondary side non-contact charging module 42includes a magnet, primary side non-contact charging module 41 canreduce the influence of the magnet.

Further, by using the Mn—Zn ferrite sheet as the ferrite sheet, it ispossible to make magnetic sheet 51 even further thinner. That is, afrequency of electromagnetic induction is defined by the standards (WPC)to be approximately 100 kHz to 200 kHz (for example, 120 kHz). In such alow frequency band, the Mn—Zn ferrite sheet exhibits high efficiency.The Ni—Zn ferrite sheet exhibits high efficiency in high frequency.

[Regarding a Mobile Terminal and a Secondary Side Non-Contact ChargingModule]

A case where secondary side non-contact charging module 42 is mounted ona mobile terminal device will be described.

FIG. 5 illustrates a configuration of a mobile terminal device accordingto the embodiment of the present invention, and is a perspective viewwhich illustrates a decomposed mobile terminal device.

Mobile terminal device 520 is composed of liquid crystal panel 521,operation button 522, substrate circuit board 523, battery pack 524, andthe like. Mobile terminal device 520 which receives power by utilizingelectromagnetic induction action has secondary side non-contact chargingmodule 42 inside chassis 525 and chassis 526 which form its exterior.

At a back surface of chassis 525 on which liquid crystal panel 521 andoperation button 522 are provided, substrate circuit board 523 includinga controlling section which receives information input from operationbutton 522, displays necessary information on liquid crystal panel 521and controls the whole of mobile terminal device 520 is provided.Further, at a back surface of substrate circuit board 523, battery pack524 is provided. Battery pack 524 is connected to substrate circuitboard 523 and supplies power to substrate circuit board 523.

Further, at a back surface of battery pack 524, that is, at the side ofchassis 526, secondary side non-contact charging module 42 is provided.Secondary side non-contact charging module 42 receives power supply fromprimary side non-contact charging module 41 by the action ofelectromagnetic induction and charges battery pack 524 by utilizing thepower.

Secondary side non-contact charging module 42 includes secondary sidecoil 21b, magnetic sheet 52, and the like. When power supply is assumedto be received from the side of chassis 526, by arranging secondary sidecoil 21b and magnetic sheet 52 in this order from the side of chassis526, it is possible to receive power supply while reducing the influenceof substrate circuit board 523 and battery pack 524.

Further, secondary side non-contact charging module 42 may have magnet30b to be used for performing positioning with primary side non-contactcharging module 41. In this case, magnet 30b is provided at a hollowportion positioned in a central area of secondary side coil 21b. It isdefined by the standards (WPC) that magnet 30b should be a circle andshould have a diameter of 15.5 mm or less, for example. Magnet 30b has acoin shape and has to be arranged so that its center matches a centralwinding axis of primary side coil 21a in order to reduce the influenceof magnet 30a on primary side coil 21a. Magnet 30b provided at secondaryside non-contact charging module 42 reduces the L values of both primaryside coil 21a and secondary side coil 21b.

When secondary side non-contact charging module 42 has magnet 30b, asthe first method for arranging magnet 30b, there is a method in whichmagnet 30b is arranged on an upper surface of central portion 32b ofmagnetic sheet 52. Further, as the second method for arranging magnet30b, there is a method in which magnet 30b is arranged in place ofcentral portion 32b of magnetic sheet 52. In the second method, becausemagnet 30b is arranged in a hollow area of secondary side coil 21b, itis possible to make secondary side non-contact charging module 42smaller.

When a magnet is not utilized for positioning primary side non-contactcharging module 41 and secondary side non-contact charging module 42,magnet 30b is not required.

Secondary side non-contact charging module 42 will be described.

FIG. 6 illustrates a secondary side non-contact charging moduleaccording to the embodiment of the present invention and illustrates acase where a secondary side coil is a circular coil.

FIGS. 7A to 7D illustrate in detail a secondary side non-contactcharging module according to the embodiment of the present invention.FIGS. 7A to 7D illustrate an upper surface of the secondary sidenon-contact charging module, FIG. 7B is a cross-sectional view of C-C ofthe secondary side non-contact charging module in FIG. 7A, FIG. 7C is across-sectional view of D-D of the secondary side non-contact chargingmodule in FIG. 7A when a linear recessed portion is provided, and FIG.7D is a cross-sectional view of D-D of the secondary side non-contactcharging module in FIG. 7A when a slit is provided. It should be notedthat FIG. 7A and FIG. 7B illustrate a case where magnet 30b is notprovided. If a magnet is provided, magnet 30b indicated by the dottedline is provided.

FIG. 6 and FIGS. 7A to 7D which illustrate secondary side non-contactcharging module 42 respectively correspond to FIG. 3 and FIGS. 4A to 4Dwhich illustrate primary side non-contact charging module 41. Theconfiguration of secondary side non-contact charging module 42 isbasically substantially the same as that of primary side non-contactcharging module 41.

Secondary side non-contact charging module 42 differs from primary sidenon-contact charging module 41 in the size and material of magneticsheet 52. Magnetic sheet 52 to be used in secondary side non-contactcharging module 42 has a size within approximately 40×40 mm and has athickness of approximately 2 mm or less.

The size of magnetic sheet 51 to be used in primary side non-contactcharging module 41 differs from the size of magnetic sheet 52 to be usedin secondary side non-contact charging module 42 because secondary sidenon-contact charging module 42 is typically mounted on a portableelectronic device, and therefore requires to be smaller. In thisembodiment, magnetic sheet 52 is a substantially rectangle ofapproximately 20 mm×25 mm. Magnetic sheet 52 is preferably formed tohave about the same size as or to be larger than an outer periphery endof secondary side coil 21b. Further, the shape of magnetic sheet 52 maybe a circle, a rectangle, a polygon, or a rectangle or a polygon havinglarge curves at four corners.

Further, because secondary side non-contact charging module 42 is usedat a mobile terminal which is power supply reception side, there is noextra space which can be occupied by secondary side non-contact chargingmodule 42 in the mobile terminal. Further, because a current flowingthrough secondary side coil 21b of secondary side non-contact chargingmodule 42 is small, high insulation of magnetic sheet 52 is notrequired. In this embodiment, secondary side coil 21b includes aconductive wire of approximately 0.18 to 0.35 mm, and among them,secondary side coil 21b of secondary side non-contact charging module 42preferably includes a conductive wire of approximately 0.18 to 0.30 mm.

If secondary side non-contact charging module 42 is mounted on a mobilephone, secondary side non-contact charging module 42 is often arrangedbetween a casing that forms the exterior of the mobile phone and abattery pack positioned inside the case. Typically, the battery packwhich is an aluminum chassis, negatively affects on power transmissionbecause the magnetic flux of the coil is weakened due to occurrence ofan eddy current generated in aluminum in a direction which weakens themagnetic flux generated by the coil. Therefore, it is necessary toprovide magnetic sheet 52 between aluminum which is the exterior of thebattery pack and secondary side coil 21b arranged on the exterior toreduce influence on the aluminum.

Taking into account the above, it is important to use magnetic sheet 52having high magnetic permeability and high saturation magnetic fluxdensity in secondary side non-contact charging module 42 to increase theL value of secondary side coil 21b as high as possible. Basically, aswith magnetic sheet 51, magnetic sheet 52 may have magnetic permeabilityof 250 or higher and saturation magnetic flux density of 350 mT orhigher. In this embodiment, magnetic sheet 52 is preferably a Mn—Znferrite sintered compact having magnetic permeability of 1,500 orhigher, saturation magnetic flux density of 400 or higher, and athickness of approximately 400 μm or greater. However, it is alsopossible to use a Ni—Zn ferrite, and with magnetic permeability of 250or higher and saturation magnetic flux density of 350 or higher, it ispossible to transmit power with primary side non-contact charging module41. Further, secondary side coil 21b is also wound in a substantiallyrectangular shape as with primary side coil 21a. There is a case wheremagnet 30a is provided inside primary side non-contact charging module41 to perform positioning and a case where positioning is performedwithout magnet 30a being provided. When a magnet is provided at primaryside non-contact charging module 41, the diameter of circular magnet 30ais 15.5 mm or less, and in this embodiment, 15.5 mm.

A relationship between the size of magnet 30a and the size of a hollowportion of secondary side coil 21b will be described. While a case wheremagnet 30a is provided at primary side non-contact charging module 41will be described here, the relationship is the same as a case wheremagnet 30b is provided at secondary side non-contact charging module 42,in which case, in the following description, magnet 30b corresponds tomagnet 30a, and primary side non-contact charging module 41 correspondsto secondary side non-contact charging module 42.

In addition, there is, for example, the following methods forpositioning primary side non-contact charging module 41 and secondaryside non-contact charging module 42. For example, there is a method inwhich the non-contact charging modules are physically (as a shape) andforcibly positioned by forming a protruding portion on a chargingsurface of a charger and forming a recessed portion on a secondary sideelectronic device and fitting the protruding portion into the recessedportion. There is still another method in which the non-contact chargingmodules are positioned by mounting a magnet on at least one of theprimary and secondary side non-contact charging modules and by themagnets provided at the both non-contact charging modules or the magnetprovided at one non-contact charging module and a magnetic sheetprovided at the other non-contact charging module being attracted byeach other. There is yet another method in which the primary sidenon-contact charging module detects a position of a coil of thesecondary side non-contact charging module to thereby automatically movea coil of the primary side non-contact charging module to the positionof the coil of the secondary side non-contact charging module. There isstill another method in which a large number of coils are provided at acharger to thereby enable charging even if a mobile device is placed onanywhere on a charging surface of the charger.

While, as described above, there are various methods for positioningcoils of primary side (charging side) non-contact charging module 41 andsecondary side (charged side) non-contact charging module 42, thesemethods can be divided into a method in which a magnet is used and amethod in which a magnet is not used. By making primary side (chargingside) non-contact charging module 41 applicable to both secondary side(charged side) non-contact charging module 42 in which a magnet is usedand secondary side (charged side) non-contact charging module 42 inwhich a magnet is not used, it is possible to perform chargingregardless of types of the secondary side (charged side) non-contactcharging module, so that convenience can be improved. In a similarmanner, by making the secondary side (charged side) non-contact chargingmodule applicable to both the primary side (charging side) non-contactcharging module in which a magnet is used and the primary side (chargingside) non-contact charging module in which a magnet is not used, it ispossible to perform charging regardless of types of the primary side(charging side) non-contact charging module, so that convenience can beimproved. That is, it is necessary to configure the non-contact chargingmodule which performs power transmission with the other non-contactcharging module which is a counterpart of power transmission usingelectromagnetic induction, so as to be able to perform positioning withthe other non-contact charging module and to perform power transmissionusing both of first means in which a magnet provided at the othernon-contact charging module is utilized to perform positioning andsecond means in which positioning is performed without utilizing amagnet.

If magnet 30a exists near secondary side non-contact charging module 42in order to perform positioning, magnetic permeability of magnetic sheet52 is lowered. The magnetic permeability of magnetic sheet 52 becomesthe lowest at a portion close to magnet 30a (typically, near centralportion 32b), and a lowering rate of the magnetic permeability isreduced (the magnetic permeability becomes less likely to be lowered) inaccordance with an increase in distance from magnet 30a. If the magneticpermeability of magnetic sheet 52 decreases, the L value of secondaryside coil 21b is lowered. Accordingly, by increasing a distance betweensecondary side coil 21b and magnet 30a, it is possible to suppressdecrease of the L value. Meanwhile, in order to make the non-contactcharging modules smaller, it is difficult to increase the distancebetween secondary side coil 21b and magnet 30a. This will be describedin detail below.

FIGS. 8A to 8D illustrate a relationship between a primary sidenon-contact charging module provided with a magnet and a secondary sidenon-contact charging module. FIG. 8A illustrates a case where a magnetfor performing positioning is used when an inner width of a coil issmall, FIG. 8B illustrates a case where a magnet for positioning is usedwhen the inner width of the coil is large, FIG. 8C illustrates a casewhere a magnet for positioning is not used when the inner width of thecoil is small, and FIG. 8D illustrates a case where a magnet forpositioning is not used when the inner width of the coil is large. FIG.9 illustrates a relationship between a coil inner diameter and the Lvalue of the coil. FIGS. 8A to 8D illustrate primary side non-contactcharging module 41 provided with magnet 30a and secondary side coil 21bof secondary side non-contact charging module 42 which performs powertransmission. It should be noted that the description of secondary sidecoil 21b of secondary side non-contact charging module 42 which will bedescribed below can be also applied to primary side coil 21a of primaryside non-contact charging module 41 which performs power transmissionwith secondary side non-contact charging module 42 provided with magnet30b.

Primary side coil 21a faces secondary side coil 21b. In primary sidecoil 21a and secondary side coil 21b, a magnetic field is also generatedin inner portions 211 and 212, and power is transmitted. Inner portions211 and 212 face each other. Further, inner portions 211 and 212 areclose to magnet 30a, and therefore are likely to be negatively affectedby magnet 30a. That is, when a magnetic flux is generated between theprimary side coil and the secondary side coil to perform powertransmission, if a magnet exists between or around the primary side coiland the secondary side coil, the magnetic flux extends while avoidingthe magnet. Alternatively, a magnetic flux which penetrates inside themagnet causes an eddy current or heat inside the magnet, which becomes aloss. Further, as a result of the magnet being arranged near themagnetic sheet, the magnetic permeability of the magnetic sheet near themagnet is lowered. Accordingly, magnet 30a provided at primary sidenon-contact charging module 41 weakens the magnetic flux of primary sidecoil 21a and secondary side coil 21b, particularly, at inner portions211 and 212, which causes a negative effect. As a result, transmissionefficiency between the non-contact charging modules is lowered.Therefore, in a case of FIG. 8A, inner portions 211 and 212 which arelikely to be negatively affected by magnet 30a become large. Meanwhile,in FIG. 8C in which a magnet is not used, because the number of turns ofsecondary side coil 21b is large, an L value becomes great. As a result,because a lowering rate from the L value in FIG. 8C to the L value inFIG. 8A is considerably high, in the coil having a small inner width, alowering rate of the L value from a case where magnet 30a is providedfor positioning to a case where magnet 30a is not provided becomesconsiderably high. Further, if the inner width of secondary side coil21b is smaller than a diameter of magnet 30a as shown in FIG. 8A,secondary side coil 21b is directly negatively affected by magnet 30a byan amount corresponding to an area where secondary side coil 21b facesmagnet 30a. Accordingly, the inner width of secondary side coil 21b ispreferably separate from magnet 30a as far as possible.

Meanwhile, if the inner width of the coil is large as shown in FIG. 8B,inner portions 211 and 212 which are likely to be negatively affected bymagnet 30a become very small. Further, in a case of FIG. 8D where amagnet is not used, because the number of turns of secondary side coil21b becomes small, the L value becomes smaller than the case of FIG. 8C.As a result, because a lowering rate from the L value in the case ofFIG. 8D to the L value in the case of FIG. 8B becomes small, it ispossible to suppress the lowering rate of the L value in the coil havinga large inner width. Further, because an end of the hollow portion ofcoil 21 is separate from magnet 30a in accordance with an increase ininner width of secondary side coil 21b, it is possible to suppress theinfluence of magnet 30a. However, because the non-contact chargingmodule is mounted on a charger, electronic device, or the like, it isnecessary to make the non-contact charging module smaller and it isimpossible to form the non-contact charging module having apredetermined size or larger. Therefore, in order to reduce a negativeeffect of magnet 30a by increasing the inner widths of primary side coil21a and secondary side coil 21b, the number of turns is reduced and theL value becomes small regardless of the presence or absence of a magnet.

Further, as shown in FIG. 9, when the size of magnet 30a and the outerdiameter of secondary side coil 21b are fixed (30 mm), if the number ofturns of secondary side coil 21b is reduced and an inner diameter ofsecondary side coil 21b is increased, the influence of magnet 30a onsecondary side coil 21b becomes small. That is, the L value of secondaryside coil 21b in a case where magnet 30a is utilized to position primaryside non-contact charging module 41 and secondary side non-contactcharging module 42 becomes close to the L value in a case where magnet30a is not utilized. Accordingly, the resonant frequency in a case wheremagnet 30a is used becomes very close to the resonant frequency in acase where magnet 30a is not used. The result of FIG. 9 can be alsoapplied to the L value of primary side coil 21a of primary sidenon-contact charging module 41 when magnet 30b is provided at secondaryside non-contact charging module 42.

As described above, the present invention employs a configuration suchthat a substantially rectangular hollow portion of secondary side coil21b has a short side shorter than a diameter of the aforementionedcircular magnet and a long side longer than the diameter of theaforementioned circular magnet. That is, because the diameter of magnet30a is 15.5 mm at a maximum, the long side is preferably longer than15.5 mm. By this means, even if the short side is shorter than 15.5 mm,it is possible to provide an effect of the present invention to anymagnet. This will be described in detail using FIGS. 10A and 10B.

FIGS. 10A and 10B illustrate a relationship between a secondary sidecoil wound in a rectangular shape and a secondary side coil wound in acircular shape and a magnet provided at a primary side non-contactcharging module. FIG. 10A illustrates a case where the secondary sidecoil is wound in a rectangular shape, and FIG. 10B illustrates a casewhere the secondary side coil is wound in a circular shape. It should benoted that in FIGS. 10A and 10B, the length of an outer long side of therectangular coil shown in FIG. 10A is equal to a diameter of an outerdiameter of the circular coil shown in FIG. 10B, and both are n, and aninner long side y of the rectangular coil is equal to a diameter x of aninner circle of the circular coil. Further, an inner short side of therectangular coil is z. Naturally, x>z, and y>z. It should be noted thatin this case, a coil is secondary side coil 21b provided at secondaryside non-contact charging module 42. In order to sufficiently secure adistance between an inner circle (outer periphery of the hollow portion)of circular coil 2d and magnet 30a, it is necessary to set x greaterthan m. As a result, a height and a width of the circular coil are n inany direction. Further, a distance between the inner circle (outerperiphery of the hollow portion) of circular coil 2d and magnet 30a is(x−m)/2 at any angle in FIG. 10B. That is, the distance between theinner circle (outer periphery of the hollow portion) of circular coil 2dand magnet 30a is (x−m)/2 at a maximum and at a minimum.

Meanwhile, in rectangular coil 2c shown in FIG. 10A, part of a long sideportion overlaps with magnet 30a. That is, z<m. However, corner portions(four corners) and a short side portion of rectangular coil 2c do notoverlap with magnet 30a (y>m). Further, because a diagonal of therectangle is greater than y, a distance from magnet 30a to the cornerportions is greater than (x−m)/2. Further, in the case of therectangular coil, the magnetic flux concentrates on the corner portions,because if the coil is wound so as to form a corner, a magnetic fluxconcentrates on the corner portion. Further, when the coil is wound in arectangular shape, a magnetic flux concentrates on the short side ratherthan the long side. The shortest distance between the short side ofrectangular coil 2c in FIG. 10A and magnet 30a is (x−m)/2, and portionsother than a center of the short side is further separate from magnet30a.

That is, even if part of the long side portion of rectangular coil 2c inFIG. 10A overlaps with magnet 30a, the corner portions on which themagnetic flux concentrates most are separate from magnet 30a, and adistance between the corner portions and magnet 30a is greater than(x−m)/2. Further, a distance between the short side and magnet 30a is(x−m)/2 or greater. By this means, while rectangular coil 2c in FIG. 10Arealizes a smaller size compared with circular coil 2d in FIG. 10B,rectangular coil 2c can perform power transmission with the sameefficiency as that of the circular coil.

It should be noted that the substantially rectangular coil includes acoil wound so that four corners are curved, instead of right angled. Atthis time, it is only necessary to set each of the curved shapes at fourcorners at 30% or less of a corresponding one of the sides of the hollowportion. For example, if the rectangular hollow portion is 12 mm×18 mm,it is only necessary to set each of the curves of the hollow portion tobe 3.6 mm or less at both sides of the short side and 5.4 mm or less atboth sides of the long side. The outer shape (outer edge shape) of thecoil varies according to the shape of the hollow portion. If each curvedshape of the four corners is 30% or greater of a corresponding side ofthe hollow portion, the rectangular shape becomes an elliptic shape. Ifthe coil has an elliptic shape, a phenomenon that the magnetic fieldconcentrates on the corners is weakened, and the corners come close tomagnet 30a. Accordingly, the curved shape of the four corners is set at30% or less.

In the non-contact charging module in FIG. 10A, when a magnet isprovided at the non-contact charging module which is a powertransmission counterpart, the L value is approximately 9.2 μH, and whena magnet is not provided, the L value is approximately 26.4 μH, and thelowering rate of the L value is approximately 65%. Meanwhile, in thenon-contact charging module in FIG. 10B, when a magnet is provided atthe non-contact charging module which is a power transmissioncounterpart, the L value is approximately 9.7 μH, when a magnet is notprovided, the L value is approximately 27.6 μH, and the lowering rate ofthe L value is approximately 65%. That is, the non-contact chargingmodules shown in FIG. 10A and FIG. 10B exhibit almost the same L valueand lowering rate of the L value.

Accordingly, the substantially rectangular coil in FIG. 10A can reducethe area of the coil by approximately 15% while realizing almost thesame property as the circular coil in FIG. 10B. Further, when magneticsheet 52 is mounted on a mobile terminal as shown in FIGS. 10A and 10B,a substantially rectangular magnetic sheet is often used taking intoaccount an arrangement of other parts, and magnetic sheet 52 in FIG. 10Areduces an area of magnetic sheet 52 by approximately 30% or greatercompared to magnetic sheet 52 in FIG. 10B.

If the coil is formed to have a substantially square hollow portion of18 mm×18 mm, the lowering rate of the L value becomes considerably lowand approximately 56%, so that it is possible to form the non-contactcharging module having more favorable power transmission efficiency.However, it is impossible to realize a smaller non-contact chargingmodule with such a coil having the substantially square hollow portion.

By providing secondary side coil 21b in which a conductive wire is woundin a substantially rectangular shape and magnetic sheet 52 provided witha surface on which secondary side coil 21b is placed and by making theshort side of the substantially rectangular hollow portion of secondaryside coil 21b shorter than the diameter of circular magnet 30a, and bymaking the long side longer than the diameter of circular magnet 30a asin the present invention, it is possible to realize smaller secondaryside non-contact charging module 42 which can suppress variation of theL value of secondary side coil 21b provided at secondary sidenon-contact charging module 42 when primary side non-contact chargingmodule 41 and secondary side non-contact charging module 42 arepositioned, in both of a case where magnet 30a provided at primary sidenon-contact charging module 41 which is a power transmission counterpartis used and a case where magnet 30a is not used, and which can besuitably used in both of a case where magnet 30a is used and a casewhere magnet 30a is not used. Naturally, technique and effects ofsecondary side non-contact charging module 42 and magnet 30a can be alsoapplied to primary side non-contact charging module 41 and magnet 30b.

While the long side of the hollow portion overlaps with the magnet inthis way, the outer shape of the coil is preferably larger than themagnet. By this means, because there is a portion where the coil doesnot overlap with the magnet even in a long side portion of the coil, itis possible to reduce influence of the magnet. It should be noted thatthe lowering rate of the L value indicates a rate of the L value in acase where a magnet is used for positioning at the non-contact chargingmodule which is a power transmission counterpart with respect to the Lvalue in a case where a magnet is not used. That is, as the loweringrate of the L value is smaller, it is less likely to receive influenceof the magnet, and the L value in a case where the magnet is usedbecomes close to the L value in a case where the magnet is not used.Further, the non-contact charging device is an electronic device whichis provided with a non-contact charging module, and includes variouselectronic devices such as a charger provided with the primary sidenon-contact charging module, and a mobile terminal or an electronicdevice, provided with the secondary side non-contact charging module.

The disclosure of Japanese Patent Application No. 2011-195819, filed onSep. 8, 2011, including the specification, drawings, and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

According to the non-contact charging module, electronic device andnon-contact charging device of the present invention, it is possible torealize smaller non-contact charging module, electronic device andnon-contact charger which can realize high efficiency and stable powertransmission efficiency. Thus, the present invention is suitable for useas a transmission side charging device for charging a mobile device suchas a mobile phone, a portable audio, a mobile terminal such as a mobilecomputer, a digital camera and a video camera.

REFERENCE SIGNS LIST

-   21a Primary side coil-   21b Secondary side coil-   211, 212 Inner portion-   22a, 23a Terminal (primary side)-   22b, 23b Terminal (secondary side)-   30a Magnet (primary side)-   30b Magnet (secondary side)-   31a Flat portion (primary side)-   31b Flat portion (secondary side)-   32a Central portion (primary side)-   32b Central portion (secondary side)-   33a Linear recessed portion (primary side)-   33b Linear recessed portion (secondary side)-   34a Slit (primary side)-   34b Slit (secondary side)-   41 Primary side non-contact charging module (transmission side    non-contact charging module)-   42 Secondary side non-contact charging module (reception side    non-contact charging module)-   51 Magnetic sheet (primary side)-   52 Magnetic sheet (secondary side)-   71 Power input section-   72 Rectifier circuit-   82 Power output section-   200 Electronic device-   300 Commercial power source-   301 Outlet-   400 Non-contact charger-   401 Plug-   402 Surface-   5010n table501 Table-   520 Mobile terminal device-   521 Liquid crystal panel-   522 Operation button-   523Substratecircuit board-   524 Battery pack (power holding section)-   525, 526 Chassis

The invention claimed is:
 1. A system comprising: a mobile terminal thatincludes a rectangular-shaped housing; a circuit board and a batteryincluded in the housing, the circuit board controlling operation of themobile terminal and supplied with power from the battery; and a firstnon-contact charging module configured to perform power transmissionwith included in the housing; and a second non-contact charging moduleby electromagnetic induction including a circular magnet and configuredto be positioned with the second relative to the first non-contactcharging module using a in reference to the circular magnet or withoutusing the circular magnet for positioning, the circular magnet beingprovided at the second non-contact charging module, wherein the firstnon-contact charging module comprisingincludes: a planar coil portionincluding a conductive wire wound in a rectangular shape; and a magneticsheet provided with a surface on which the planar coil portion isplaced, wherein the planar coil portion includes a rectangular-shapedhollow portion that has a plurality of short sides shorter than adiameter of the circular magnet and a plurality of long sides longerthan the diameter of the circular magnet, the rectangular-shaped hollowportion of the planar coil portion has an outline in which every shortside and long side of the outline is longer than the diameter of thecircular magnet, the long side of the outline is in parallel to a longside of the rectangular-shaped housing, and a distance from the longside of the outline to the closest long side of the rectangular-shapedhollow portion defines a width of the planar coil portion that is longerthan the short side of the rectangular-shaped hollow portion, and thecircular magnet is positioned on top of the planar coil portion, andwherein the first non-contact charging module overlaps with the batteryand with the circuit board in the housing.
 2. A first non-contactcharging device comprising the non-contact charging module according toclaim
 1. 3. The first non-contact charging module system according toclaim 1, wherein the rectangular-shaped hollow portion includes aplurality of corner portions, and the circular magnet does not overlapwith either the plurality of short sides of the rectangular-shapedhollow portion or the plurality of corner portions of therectangular-shaped hollow portion.
 4. A system comprising: a mobileterminal that includes a rectangular-shaped housing; a circuit board anda battery included in the housing, the circuit board controllingoperation of the mobile terminal and supplied with power from thebattery; and a first non-contact charging module configured to performpower transmission with included in the housing; and a secondnon-contact charging module by electromagnetic induction including acircular magnet and configured to be positioned with the second relativeto the first non-contact charging module using a in reference to thecircular magnet or without using the circular magnet for positioning,the circular magnet having a diameter of 15.5 mm at maximum and beingprovided at the second non-contact charging module, wherein the firstnon-contact charging module comprisingincludes: a planar coil portionincluding a conductive wire wound in a rectangular shape; and a magneticsheet provided with a surface on which the planar coil portion isplaced, wherein the planar coil portion includes a rectangular-shapedhollow portion that has a short side shorter than 15.5 mm and a longside longer than 15.5 mm, the rectangular-shaped hollow portion of theplanar coil portion has an outline in which every short side and longside of the outline is longer than the diameter of the circular magnet,the long side of the outline is in parallel to a long side of therectangular-shaped housing, and a distance from the long side of theoutline to the closest long side of the rectangular-shaped hollowportion defines a width of the planar coil portion that is longer thanthe short side of the rectangular-shaped hollow portion, and thecircular magnet is positioned on top of the planar coil portion, andwherein the first non-contact charging module overlaps with the batteryand with the circuit board in the housing.
 5. The first non-contactcharging module system according to claim 4, wherein therectangular-shaped hollow portion includes a plurality of cornerportions, and each corner portion of the plurality of corner portionsincludes a curved shape that starts to curve at a distance equal to 30%or less of a corresponding long side and 30% or less of a correspondingshort side of the rectangular-shaped hollow portion.
 6. The firstnon-contact charging module system according to claim 5, wherein thediameter of the circular magnet is greater than half a distance of adifference between a length of the long side of the rectangular-shapedhollow portion and the diameter of the circular magnet.
 7. The systemaccording to claim 4, wherein a diameter of the conductive wire of theplanar coil portion is approximately 0.18 to 0.30 mm.
 8. The systemaccording to claim 1, wherein a diameter of the conductive wire of theplanar coil portion is approximately 0.18 to 0.30 mm.